One thing I don't recollect ever seeing were mochi as vividly colored as the ones pictured above. Most of the tones I saw were closer to pastels and these are more akin to jewel tones. Though these have Japanese writing on them, they were made in another Asian country (likely China or Taiwan, but I don't remember). My guess is that this sort of color can only come with the use of artificial coloring and that is frowned upon in Japan.
Though these are actually very pretty and reasonably priced, one of the lasting impacts of life in Japan for me has been a suspicion of anything which clearly shows unnatural coloring. I'd rather buy a muddy-looking or grey blob of mochi that looked real than something lovely such as these.